I tried posting on the hondata forums but it seems like there isn't a ton of help over there lately (not many people checking the threads). This is my thread copied from over there.

I recently purchased a 97 civic with a fully tuned lsvtec motor. The motor setup isn't really anything too crazy, 81.5 b16 style pistons and ctr cams with a minor valve job on a b16 head with a S2 pro mani and 66mm TB. Motor is NA.

I was told that the car was tuned for 6 hours on a dyno dialing in the tune very well. It runs great, with no issues really, but the fuel economy is way worse then I would expect for the setup. I've seen similar engines with bigger cams get better fuel economy then this thing. I don't currently have a wide band, because when I bought it I was told the wideband o2 had gone bad (reads 14.8 consistently),I just got the car a few days ago and haven't replaced it, so I don't know if the car is running really rich or not, but it smells pretty rich. I tried to upload the calibration but for some reason when I click browse in the attachments section I can't find my calibration, even though it is saved on my computer in the calibrations section and I can open it perfectly fine with Smanager. I tried to type in the file name manually, but when I click open it tells me the file name cannot be found. All of the pre saved calibrations can be attached, but I cannot attache my saved calibration. If someone knows of a better way to attach a calibration or knows what I'm doing wrong that would be great.

I guess I'm just looking for a bit of advice on how to possibly tune for better fuel economy. I'm not looking for amazing gas mileage, but it would be nice to save a few gallons in the cruising RPM's. How lean is too lean? Should I just shoot for slightly higher then stoich and add a degree or two of timing to aid the combustion? Comparing my fuel tables to the stock ITR tables in row six, the ITR fuel values are actually a bit higher than mine from about about 2000 to 3000 RPM's, then after that my tune jumps ahead quite a bit from 3000 through about 4500. I was thinking that I could pull a tad bit of fuel in the 2000-4200 cruising range, monitor the wideband, and aim for a slightly leaner then stoich mixture and be fine if I add a tad of timing. Is this a practical and safe method for street tuning for better MPG's? Would it be too dangerous to run in say the 15.2 AFR range? I'm pretty new at this hands on ECU tuning and would hate to ruin a perfectly running engine. If when I get the wide band it does in fact appear to be running quite rich it would be safe to say that I could get away with making it run more stoich and probably save some gas without having to go lean but I figured I would look for some insight on the best way to go about doing this without being on a dyno and paying someone else to do it for me. Thanks for any help.

 

Get yourself a new 5volt o2 sensor and then think about tuning. Cruising at low 15's to high 15's should not be a problem. SOmetimes I even cruise in the low 16 AFR range

 

Thanks for the reply. I had no intentions of messing with the map until I get the wideband situation fixed. 16's AFR seem a bit high, I mean, if you're able to do it safely then it must be fine for your set up but I was under the impression that cruising around that high could be bad. What's your set up if you don't mind me asking? Did you tune it yourself, and if so, did you advance the ignition at all in the spots where you are cruising around in a high lean condition such as upper 15's low 16's? Thanks.

 

Thanks for chiming in. The car is pretty much about as light as it's going to get, considering that all unnecessary things have already been taken off of it and the things I'd like the keep, like a full interior for instance are going to stay. The car is kind of more of a daily then a race car for me. Also, it was already dyno tuned pretty well to make power. I'm not planning on going back to the dyno to have tuned to make more torque. More torque usually requires more fuel as well, which sort of defeats the purpose of my current goal. Generally, where peak torque occurs on the dyno plot, the map requires pretty close to the most fuel throughout the RPM's. I'm simply looking to take a bit of fuel away during the cruising rpm's, even if I have to sacrifice some torque to get there.

 

Bump. Looking for a bit more advice before I try to tackle this.

 

Without a wideband, posting on here is pointless.
Fix your wideband, sync it to your Smanager software. Make some datalogs.
Post the calibration & datalog & maybe some one that has a clue will help you look over the log :-)

14.0:1-15.5:1 is perfectly fine at partial throttle on 91-93 octane on most setups simular to yours.

 

I'll do all of that as soon as I replace the wide band o2. How do I go about posting a calibration on here, as an attachment? I'll try...

When I try to upload the calibration it at first could not be found with the rest of the calibrations, where my calibration is saved, so I made a a second save on the desk top and when I tried to attach it the manager said that it is an invalid file. How do I go about uploading a calibration for viewing? Do I have to change the file type to something that Honda-tech supports as an attachment? Thanks.